PDS22MHRBBB refrigerator. Stops cooling good a few days after I defrost it.When I first took it apart I noticed a lot of frost build up on the coils in the freezer so I defrosted it, but after a few days it's frosted back up again, why?I have never had to defrost it before and we have had it for years. Is there something else i can do beside to keep defrosting it?It works great for the first few days after I defrost it.

You can check the defrost circuit from the main control board on the back with an ohm meter. Usually it take a couple weeks to really frost up bad enough to cause large cooling issues. How are your door seals?